Climate change to worsen Eastern Australia’s winter pollution

Asthmatics and those affected by polluted environments living around major cities along Australia’s east coast could find life much harder over the next 50 years as stronger inversion layers caused by climate change trap more pollution.

New research from the ARC Centre of Excellence for Climate Extremes (CLEX) published in Climate Dynamics reveals inversion layers in east coast cities will be 40-80% stronger as a result of climate change – especially during winter.

Most inversion layers occur in winter because the conditions that favour their development are calm winds, clear skies and long nights.

“Even though Australia has relatively clean air by world standards, it has been estimated that 3000 premature deaths every year are linked to urban air pollution,” said co-author and chief investigator with CLEX Prof Jason Evans.

“This number of premature deaths could increase with stronger low-level inversion events making poor air quality even worse. We found that along with the changes in strength, as we move further south towards Melbourne and Adelaide, the influence of climate change made inversions last longer.”

The researchers combined observations of inversion layers from 1990-2009 extending from Brisbane to Adelaide and inland to get their results. They then tested a suite of climate models to select those that produced results that most closely mirrored observations. The best models were used to determine how inversion layers would respond to future climate change.

The results showed the overall frequency of low-level inversions did not change. However there was a slight increase in the number of daytime temperature inversions, which suggested there would likely be more adverse air quality impacts as there is generally more pollution during daylight hours.

There were also very slight changes in how long inversion layers persisted, with the length decreasing in the northern cities and increasing in duration to the South.

The big change was in the strength, which is a measure of the difference in temperature between the warm air at the top of an inversion layer compared to the cooler air above the land surface. Stronger inversions with greater temperature differences have the capacity to trap more pollutants.

“Even though the overall number of inversions didn’t change, we saw a substantial reduction in weak inversions and a marked increase in stronger inversion layers,” Prof Evans said.

“These changes to the pollutant trapping power of inversion layers occur where 80% of Australia’s population is found. With our population expected to continue increasing in these regions, the impact of more intense air pollution events in the next 50 years could be substantial.”